When the operation of the disk device is stopped, the actuator mounting the signal converting element is unload-operated from an area for recording data, and is moved and held in a predetermined area (parking zone) on a recording medium. Otherwise, the actuator is moved and held in a predetermined position near the outer circumference of the recording medium in which no signal converting element comes in contact with the surface of the recording medium. Namely, when the operation of the disk device is stopped, the actuator is held in a predetermined escaping position. Further, when an impact from the exterior is applied at the stopping time of the operation of the disk device, the actuator is moved from the escaping position to the data recording area on the recording medium, and the data area surface on the recording medium is damaged by a collision of the signal converting element and the recording medium surface. Otherwise, the data area surface on the recording medium is damaged by a sliding movement with respect to the signal converting element due to an operation start from a state in which the actuator comes in contact with the data recording area at the moving time to the data recording area as it is. Otherwise, a separate constructional part of the disk device and the actuator collide so that the constructional part and the actuator are damaged. A holding member or a holding method of the actuator for holding the actuator in the predetermined escaping position is adopted so as not to cause such fatal breakdowns.
An example of the disk device having the holding member of the conventional actuator will be explained next. First, with respect to a disk drive unit having the holding member of the actuator, a converting head (corresponding to the above signal converting element) is attached to one end of an actuator arm. A coil is attached to the other end of the actuator arm. A projection is integrally arranged on the other end side of the actuator arm. An iron piece is attached to the projection, and is rotatably attached around a rotary shaft so that the actuator as a voice coil motor (hereinafter called VCM) is constructed. Further, a permanent magnet is fixed to a housing so as to be opposed to the iron piece arranged in the actuator arm. The iron piece arranged in the actuator arm is magnetically attracted by the permanent magnet fixed to the housing. The actuator arm is fixed by the magnetic attractive force of the permanent magnet. Such a construction is proposed. In this example, the iron piece arranged in the actuator arm and the permanent magnet fixed to the housing function as the head holding member, and the head holding method using the magnetic attractive force generated by the permanent magnet is adopted.
In such a construction, at the stopping time of the operation of the disk drive unit, an electric current is supplied to a coil of the VCM, and the actuator arm is operated so as to be moved to the predetermined escaping position. When the actuator arm approaches the predetermined escaping position, the iron piece is attracted to the permanent magnet and the actuator arm can be fixed in the escaping position. In this state, even when an external force is applied, the actuator arm is fixed by the magnetic attractive force so that no actuator arm is moved. The data of the data recording area on the recording medium and the actuator are protected from unprepared movements of the converting head and the actuator arm (e.g., see Japanese Registered Patent No. 2803693).
With respect to an actuator lock method of the disk drive unit having the holding member of the actuator, the holding member of an actuator arm, similar to that of the example of the disk drive unit having the holding member of the above actuator, is arranged. Further, the holding member of an actuator arm constructed by a leaf spring having elasticity and a solenoid coil is arranged. The leaf spring having elasticity so as to be engaged with the actuator in the vertical direction and having stress in the upward direction is vertically moved in accordance with the movement of a plunger manufactured by iron and generated by supplying an electric current to the solenoid coil. A magnet as a first magnetic field supply means having a first magnetic force is arranged on the lower side of the plunger. A VCM yoke as a second magnetic field supply means having a second magnetic force is arranged on the upper side of the plunger. When a first electric current is supplied to the solenoid coil, magnetic force for pushing-up the plunger is generated and the leaf spring is moved on the upper side. When a second electric current different from the first electric current is supplied, magnetic force for pushing-down the plunger is generated and the leaf spring is moved on the lower side. Further, the leaf spring is fixed on the lower side by the first magnetic force of the magnet having a downward magnetic force greater than the upward stress of the leaf spring. In addition to the upward stress of the leaf spring, the leaf spring is attracted and fixed on the upper side by the second magnetic force of the VCM yoke. Such a construction is proposed.
In such a construction, at the operating time of the disk drive unit, the plunger is attracted in the direction of the magnet by the first magnetic force. Further, the leaf spring is pressed on the lower side by the plunger, and is fixed so as to attain a lock release state in which the leaf spring is fixed to a height for preventing no movement of the actuator. At the stopping time of the operation of the disk drive unit, the actuator is moved to a predetermined lock position (corresponding to the above escaping position). Further, the first electric current for generating the upward magnetic force and greater than the difference between the magnitude of the first magnetic force of the magnet and the magnitude of stress of the leaf spring is supplied to the solenoid coil. The leaf spring is moved in the upward direction. The leaf spring is then moved and fixed so as to attain a lock state fixed on the upper side. Here, the electric current is supplied to the solenoid coil only at a transfer time from the lock release state to the lock state, or a transfer time from the lock state to the lock release state. When the leaf spring is in each of the lock release state or the lock state fixed on the lower side or the upper side, no electric current is supplied to the solenoid coil. At the stopping time of the operation of the disk drive unit, the magnetic attractive force using the iron piece and the permanent magnet and the leaf spring are fixed on the upper side, and the actuator is locked in the escaping position as the lock state. Thus, the actuator can be fixed with respect to the vertical direction as well as the horizontal direction, and the movement of the actuator due to an impact can be prevented (e.g., see Japanese laid-open patent gazettes of JP-A-8-221915, JP-A-10-302418 and JP-A-2002-260356, etc.).
Further, a separate example of the disk drive unit having the lock mechanism of the actuator is proposed. In this example, the disk drive unit is constructed such that the actuator is arranged so as to be rotationally moved with an actuator swinging axis as a center, and a head arm and a coil arm are arranged so as to be mutually located on opposite sides through this actuator swinging axis. The disk drive unit of this construction has the following features (1) to (8). (1) The head arm is constructed by a carriage arm and a suspension arm, and this suspension arm has a tab in which a convex portion for escaping the suspension arm to a ramp block is formed. A head slider mounting a signal converting element is mounted to the vicinity of this tab. (2) The coil arm mounting a voice coil onto its inner face is constructed by an outer arm and an inner arm. On the other hand, (3) a lamb block arranged in the escaping position of the actuator and an inertia latch mechanism are stored to the interior of an enclosure. (4) The ramp block fixed to the enclosure by screws has plural ramps convexly arranged in the horizontal direction from the side face of a ramp support. The ramp has a composite plane including a first slanting face, a top portion plane, a second slanting face, a bottom portion plane and a third slanting face. (5) The inertia latch mechanism is constructed by an inertia lever able to be swung with an inertia lever swinging axis as a center, a latch lever able to be swung with a latch lever swinging axis as a center, and a spring for holding the latch lever in an arm opening position. In inertia moments of the inertia lever and the latch lever around the respective swinging axes, the inertia moment of the inertia lever is set to be greater than that of the latch lever. (6) The inertia lever has an inertia arm and a balance arm in which a first engaging projection engaged with the latch lever in a first engaging portion, and a second engaging projection engaged with the latch lever in a second engaging portion are formed. (7) The latch lever has a latch arm and an auxiliary arm in which two spring engaging projections, a positioning projection and a latch projection engaged with an acting side end portion of the spring are formed. The positioning projection is arranged to determine an actuator opening position and an actuator latch position of the latch lever. The latch projection is arranged to be engaged with a tip portion of the inner arm of the actuator and latch the actuator when the latch lever is moved to the actuator latch position. (8) An actuator lock mechanism is constructed by the ramp block and the inertia latch mechanism, and functions as the head holding member.
In such a construction, when no disk drive unit is operated, the actuator is unloaded to the escaping position, and the tab of the suspension arm is held in the bottom portion plane of the ramp. With respect to a weak impact, a tab convex portion of the suspension arm climbs the second slanting face or the third slanting face of the ramp block. Thus, swinging energy of the head arm is attenuated and the movement of the head arm is restrained. The head arm is prevented from moving from the escaping position to the disk side or its opposite side. The ramp block functions as the holding member of the actuator for holding the head arm in the escaping position. In the operation of the inertia latch mechanism when an impact is applied to the disk drive unit at the non-operating time of the disk drive unit, torque intended to make a rotating movement in the counterclockwise direction is applied to each of the inertia lever and the latch lever with the respective swinging axes as centers when torque for making a swinging movement in the counterclockwise direction is applied to the actuator by the impact from the exterior. If the torque applied to the inertia lever is greater than resultant torque provided by the torque due to the impact applied to the latch lever, and the torque of the spring intended to rotate the latch lever in the clockwise direction with the latch lever swinging axis as a center, the inertia lever is rotated in the counterclockwise direction irrespective of the direction of the torque applied to the latch lever. In the first engaging portion, the latch lever is pulled by the first engaging projection, and is swung in the counterclockwise direction. A latch projection of the latch arm is engaged with the tip portion of the inner arm moved from a state located in the escaping position so that the actuator is latched. Thereafter, the tab of the actuator is pushed back to the bottom portion plane of the ramp block by the operation of the second slanting face of the ramp block. The engagement of the inner arm tip portion and the latch projection is released. The latch arm is returned to the actuator opening position by the operation of the spring. When torque for making the swinging movement in the clockwise direction is applied to the actuator by the impact from the exterior, torque for making a rotating movement in the clockwise direction is applied to each of the inertia lever and the latch lever with the respective swinging axes as centers. Torque intended to make the rotating movement in the clockwise direction with the latch lever swinging axis as a center is always applied to the latch lever by the spring in addition to the torque due to the impact. If the torque applied to the inertia lever is greater than resultant force provided by the torque due to the impact applied to the latch lever and the torque due to the spring in the second engaging portion, the latch lever is pushed by the second engaging projection in the second engaging portion. The latch lever is swung in the counterclockwise direction. The latch projection of the latch arm collides with a crush stop constructed by an elastic body for regulating a swinging range of the actuator, and is engaged with the inner arm tip portion rebounded in the counterclockwise direction so that the actuator is latched. The inertia moment of the inertia lever is set to be greater than the inertia moment of the latch lever such that the torque due to the impact applied to the inertia lever is greater than the torque applied to the latch lever by the impact, and the swinging movement is made in the direction of the torque of the inertia lever due to the impact. The swinging distance of the latch projection from an opening point to a latch point, the position of the latch point, the distance from the latch projection to the swinging axis, etc. are set so as to move the latch projection to the latch point before the inner arm tip portion is moved from an escaping point to the latch point. The actuator is then latched to the escaping position, and is locked. Thus, the head arm and the head slider are prevented from entering an arranging space of the disk.
However, in the holding method of the actuator used in the disk drive unit having the holding member of the above conventional actuator, the actuator arm is fixed in the escaping position of the actuator by the attractive force of the iron piece arranged in the actuator arm and the permanent magnet fixed to the housing at the stopping time of the operation of the disk drive unit. In the actuator holding method having such a construction, a comparatively high impact resisting property is provided with respect to the impact of the same direction as the rotating direction of the actuator. However, the impact resisting property with respect to a large impact applied for a short time or an impact having a vertical component with respect to the rotating direction of the actuator is comparatively low. Therefore, a problem exists in that no holding function with respect to the impact can be sufficiently shown. Further, the iron piece and the permanent magnet are required to hold the actuator in the escaping position. Therefore, a problem also exists in that the number of parts constituting the device is increased and cost is increased.
Further, in the above conventional holding method of the actuator, when a comparatively large impact is applied, it is constructed such that the actuator is held in the escaping position so as not to move the actuator located in the escaping position up to the data recording area of the recording medium. In particular, in the example for arranging the actuator holding member constructed by the lock means and the solenoid coil, the actuator is constructed so as to be held by the iron piece arranged in the actuator arm, the permanent magnet arranged in the housing, the leaf spring for gripping the actuator, the magnet for fixing this leaf spring onto the lower side, the plunger for vertically moving the leaf spring, and the solenoid coil for vertically moving the plunger. At the stopping time of the operation of the disk drive unit, the actuator is moved to the escaping position, and the leaf spring is moved in the upward direction as the plunger is vertically moved. The leaf spring is then set to the lock state, and the actuator is locked in the escaping position. Accordingly, the impact resisting property is also provided with respect to the comparatively large impact. However, when a very large impact of the same direction as the moving direction of the plunger is applied, it is necessary to set the stress onto the upper side of the leaf spring and the second magnetic force of the VCM yoke to values for resisting this impact so as to maintain the lock state of the leaf spring. Accordingly, it is necessary to flow a large electric current to the solenoid coil and generate large magnetic force so as to move the plunger in the downward direction against such large resultant force provided by the stress onto the upper side of the leaf spring and the second magnetic force of the VCM yoke, and set the leaf spring to the lock release state. Therefore, the solenoid coil is large-sized. Further, a space for arranging respective parts constituting the holding member of the actuator for locking the actuator in the escaping position is required. Therefore, a problem exists in that it becomes difficult to make the disk drive unit compact. Further, many parts are required to construct the holding mechanism of the actuator. Therefore, a problem also exists in that this requirement increases the cost of the device.
In the disk drive unit constructed such that the actuator is rotatably arranged with the swinging axis as a center and the head arm and the coil arm are arranged so as to be mutually located on the opposite sides through this swinging axis, the inertia latch mechanism is constructed by the inertia lever, the latch lever and the spring. When a comparatively large impact is applied at the non-operating time of the disk drive unit, the inertia lever is rotated and the latch lever is rotated in the counterclockwise direction irrespective of the direction of torque applied to the latch lever. Thus, the latch projection of the latch arm is engaged with the inner arm tip portion in the coil arm of the actuator moved from a state located in the escaping position, and the actuator is latched. Therefore, the inertia moment of the inertia lever is set to be greater than the inertia moment of the latch lever. In the lock mechanism of the actuator using the construction having such an inertia latch mechanism, a non-sensitive band area with respect to the impact can be set to be very small. Accordingly, reliability as the lock mechanism of the actuator is improved. However, many parts are required to construct the inertia latch mechanism. Further, a space for arranging these parts is also required. Therefore, a problem exists in that these requirements increase the cost of the device, and become an obstacle with respect to compactness.
The present invention solves the above problems, and its object is to provide a head holding member and a head holding method of the actuator having a very high impact resisting property by a very simple construction, and a disk device using the head holding member and the head holding method.